Regenerative heat exchanger, specifically air preheater



May 10, 1960 H. R. NILSSON ET AL 2,935,160

REGENERATIVE HEAT EXCHANGER, SPECIFICALLY AIR PREHEATER Filed April 17, 1953 6 Sheets-Sheet 1 (.0 (0 L0 (0 y 1960 H. R. NILSSON ETAL 2,936,160

REGENERATIVE HEAT EXCHANGER, SPECIFICALLY AIR PREHEATER Filed April 17, 1953 I 6 Sheets-Sheet 2 //v1/[/vr P5 Fly. 2 0

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REGENERATIVE HEAT EXCHANGER, SPECIFICALLY AIR PREHEATER Filed April 17, 1953 6 Sheets-Sheet 3 0 4 5 6 a w 1 m W 6 w M A t A m o 2 h J'IQ b 4 I n "w May 10, 1960 H. R. NlLSSON ET AL REGENERATIVE HEAT EXCHANGER, SPECIFICALLY AIR PREIHEATER Filed April 17, 1953 Ha 775 Faber-7 ZVa/fhr l 5/7r4 r/ Perussan May 10,1960

H. R. NILSSON ET AL REGENERATIVE HEAT EXCHANGER, SPECIFICALLY AIR PREHEA'IER Filed April 17, 1953 i M222 ;I 216 46 4 W f 70 44 Fig. 15

6 Sheets-Sheet 5 Fig.8

y 1960 H. R. NILSSON ETAL 2,936,160

REGENERATIVE HEAT EXCHANGE-R, SPECIFICALLY AIR PREHEATER 6 Sheets-Sheet 6 Filed April 17, 1953 m w s m n m A a V m W Z I 6&4 M w 5 m; I 1 P F n 4 2 2 n J Fig. 14

United States Patent REGENERATIVE HEAT EXCHANGER, SPE- CIFICALLY AIR PREHEATER Hans Robert Nilsson, Ektorp, and Walther Per Sigvard Persson, Johanneshov, Sweden, assignors, by mesne assignments, to Svenska Rotor Maskiner Aktiebolag, Nacka, Sweden, a corporation of Sweden Application April 17, 1953, Serial No. 349,344

Claims priority, application Sweden December 22, 1952 20 Claims. (Cl. 257-268) The present invention relates to rotary regenerative heat exchangers of the kind in which a rotor filled with metallic regenerative material is turned so that the material passes alternately through a stream of hot gas from which it absorbs heat and a stream of cold gas to which the absorbed heat is rejected. More particularly, the invention relates to such apparatus employed to transfer heat from (waste) combustion gases to preheat air for use in the furnace producing the gases, and for convenience but without limitation the invention will be hereinafter discussed and described in connection with air preheating apparatus.

Past development of air preheaters of the kind under discussion has led to the use of larger and larger units, rotors of upwards of twenty feet diameter and twentyfive tons weight being relatively common. Also, in order to secure most effective heat transfer it is universal practice to conduct the gas and air streams through the rotor in counter current relation so that the cold air enters the same end of the rotor from which the cooled gas is discharged and after being heated leaves the other end of the rotor which receives the hot gases. This results, in service, of a hot end and a cold end of the rotor, between which there is a substantial temperature difference and as a consequence there is a resultant distortion of the rotor, with the outer cylindrical shell tending to become conical and the entire rotor tending to dish with reference to a plane normal to the axis of rotation. In large modern preheaters, the dimensional magnitude of such distortion may be considerable.

In order to prevent short circuiting of the rotor by the heat exchanging fluids and leakage of one fluid into the duct for the other, seals are required between the ends of the rotor and the end plates of the stationary housing structure encasing the rotor. Rotor distortion of the kind discussed above makes the problem of providing effective seals extremely difiicult, particularly since the development of the art has led to the substantially universal practice of mounting the rotors by means of a center post or the like, at the axis of rotation. With a center mounting for the rotor, maximum change of clearance between the rotor and the casing occurs at the periphery of the rotor, where circumferential seals are required at each end of the rotor and where, in addition, radial seals extending from the center of the rotor must be provided. In order to take care of the very material variations in clearance that occur, a great many different kinds of sealing means have been proposed, but none have proved to be entirely satisfactory, either because of failing to provide a suificiently effective seal, too great complexity and weight, too great frictional resistance, unduly rapid wear, prohibitive cost or combinations of such deficiencies.

In order to secure minimum variation in the clearances between the rotor and the casing at the periphery of the rotor early constructions provided for the support of the rotor by means of roller supports engaging an external 'ice peripheral flange on the rotor. Because of the nature of the apparatus, only three such supports could in practice be effectively used, with resultant wear at such rapid rate as rotors became larger and heavier that the construction had to be abandoned in favor of center post mounting, even though the latter increased the difficulties of the sealing problem and increased the weight and cost of the apparatus because of the necessity for the provision of heavy cross beams to carry the centrally located bearings and the weight of the rotor. Since in the majority of installations preheaters are mounted in lofty positions, as above large power boilers, overall Weight is a highly important factor because of its influence on the cost of the supporting structure.

With the foregoing deficiencies of present constructions in mind it is therefore the general object of the present invention to provide a new and improved preheater construction which for a given size and capacity is materially lighter and less expensive than the presently best available constructions, which provides improved sealing with simple and inexpensive sealing means, and which provides further advantages the nature and details of which will appear more fully as this specification proceeds.

For a better understanding of the more detailed objects of the invention and the manner in which they may be attained in various embodiments of apparatus for carrying the invention into effect, reference may best be had to the ensuing portion of this specification, taken in conjunction with the accompanying drawings illustrative by way of example but without limitation of different examples of constructions embodying the principles of the invention.

In the drawings:

Fig. 1 is a vertical central section, taken on line 11 of Fig. 2, of a rotary regenerative heat exchanger embodying the invention.

Fig. 2 is a top plan view, partly in section of the heat exchanger shown in Fig. 1.

Fig. 3 is a fragmentary broken vertical section on enlarged scale of a part of the structure shown in Figs. 1 and 2.

Fig. 4 is a fragmentary section taken on the lines 4-4 of Figs. 3, 7 and 8.

Fig. 5 is a section similar to Fig. line 5-5 of Figs. 3, 7 and 8.

Fig. 6 is a fragmentary broken vertical section on enlarged scale showing some of the details of thecbnstruction seen in Fig. 1.

Figs. 7 and 8 are views similar to Fig. 3, certain parts being omitted for simplification, and illustrative of different bearing and seal arrangements.

Fig. 9 is a fragmentary vertical section similar to Fig. 3 and showing another form of bearing construction;

Fig. 10 is a section taken on line 10-10 of Fig. 9.

Fig. 11 is a fragmentary section similar to Fig. 9 showing still another form of bearing construction.

Fig. 12 is a section taken on line i2-12 of Fig. 11.

Fig. 13 is a fragmentary view similar to Fig. 3 showing another form of connection between the bearing and the outer shell of the rotor.

Fig. 14 is another view similar to Figs. 3 and 13 showing still another form of connection between the hearing and the rotor shell; and

Fig. 15 is a fragmentary section similar to Fig. 6 showing a form of construction suitable for centering the rotor where connections of the kind shown in Figs. 13 and 14 are used.

Referring now more particularly to Fig. 1 and related figures of the drawings, there is illustrated one suitable form of preheater for carrying the invention into effect. The apparatus shown comprises a stationary outer casing 4 taken on the the rotor and the other fluid from the rotor.

said other fluid to the rotor.

structure, indicated generally at 10, having spaced end plates 12 and 14 between which the rotor is mounted. Plate 12 is provided with two sector shaped openings or ports 16 and 18 located generally on opposite sides of an axial plane coincident with a diameter of the rotor. These ports are connected respectively with ducts 20 and 22 for conducting one of the heat exchanging fluids to Plate '14 is likewise provided with sector shaped ports 24 and 26, aligned respectively with ports 16 and 18 in plate 12 and communicating respectively with ducts 28 and 30 for conducting the first mentioned fluid from the rotor and Countercur-rent flow of the two fluids provides for most efiicient heat transfer and in accordance with that practice the apparatus illustrated is advantageously connected so that for example cold air to be heated is admitted through duct 20 and port 16 to the top of the rotor and after being heated is discharged therefrom through port 24 and duct 28, as indlcated by arrow 32, while hot gas to be cooled enters through duct 30 and port 26 to flow upwardly through the rotor and be discharged in the direction of arrow 34 through port 18 and duct 22. With such connections it will be evident that the upper end of the apparatus will be cooler than the lower end when in use and for convenience the end of the apparatus to which fluid to be heated is admitted and from which cooled fluid is discharged will be referred to as the cold end, the opposite end being referred to as the hot end. It will "be obvious that either the upper end or the lower end may be the cold end, so long as countercurrent flow relation is maintained, depending upon which ducts are connected to the sources of supply of the different fluids.

The rotor is circumferentially enclosed and supported by portions of the stationary structure extending between the end plates, which structure in the present example includes a number of peripherally spaced standards 36 "adapted to rest on suitable supporting beams 38 and connecting in rigidly spaced relation a lower ring 41 to which end plate 14 is secured and an upper ring mem ber 44, which constitutes the lower bearing member of a bearing indicated generally at 42 and having an upper bearing member indicated generally at 46 carrying the,

'4) secured to the structure by bolts, studs or the like and separately removable. From the foregoing it will be apparent that the shel '48, member 44 and ring 50 provide a circumferential casing structure encircling the rotor, and that this structure together with the end plates provides a stationary "structure encasing the rotor and providing means for supporting, it. This stationary structure provides one of the two principal components of the apparatus.

The other principal component is the rotor, indicated generally at 52, which in the present embodiment is formed by two concentric shells 54 and 56 connected by a plurality of radial partitions 58 dividing the annular space between the shells into a number of sectors which may be further subdivided by Webs 60 into a larger number of compartments adapted to be filled with regenerative heat exchanging material (not shown) in accordance with well known practice.

In accordance with a basic feature of the present invention the rotor is rotatably supported at its periphery by the bearing 42, rather than at or adjacent to its center or axis of rotation, the many advantages of periphfiber or the like.

eral support hereinafter to be pointed out being secured by the provision of bearing construction, the nature and functioning of which enables the practical and economical application of peripheral support to be obtained inexpensively and with not only a long life factor but also relative ease of repair and replacement when wear does occur.

In the construction shown the lower bearing member 44, which may be a continuous ring or made up of a number of segments, is formed with two radially spaced flanges 62 and 64 providing between them an annular recess 66 in the corners of which are located arcuate lengths of wire 68 providing lower rails upon which a multiplicity of balls 70 may roll.

The number of lengths or sections of wire in each circumference may vary and if desired each rail may consist of only one piece. The joints between adjacent ends of wire should however be staggered as seen more clearly in Fig. 5.

The upper bearing member 46 comprises a rig-id ring 72 which may be comprised of one or more suitably connected arcuate elements and has a flange 74 forming the radially inner wall of recess 76 the outer wall of which is formed by a plurality of segmental elements 78 removably clamped in position by a series of segmental driving elements 80 of channel section secured to the ring 72 by studs 82 and carrying pins 84 which form the teeth of a peripheral rack with which the driving gear 86 for turning the rotor meshes. Additional arcuate lengths of wire 68 in the corners of recess 76 provide upper rails engaged in rolling contact by balls 70, the latter being held in evenly spaced relation peripherally by the retainer 88 which is also advantageously in the form of a series of separate segmental elements.

As in the case of the lower rails, the joints in the upper rails should be staggered not only with respect to each other but also with respect to the joints in the lower rails, so that no ball passes over more than one joint at a time.

The upper end of the outer rotor shell is formed by the ring element 90 providing a peripheral flange 92 having a lower annular bearing surface 94 which rests upon the upper bearing surface 96 of the bearing member 46, which is advantageously provided with a bearing ring 98 of suitable heat insulating material such as compressed The outer diameter of flange 92 is slightly smaller in diameter than the circular shoulder 100 on the ring 72 which provides a stop for substantially centering the rotor with respect to the bearing While at the same time permitting freedom of lateral movement between the rotor flange and the bearing ring sufficient to compensate for differential expansion and contraction between the parts.

At the place where the rotor is supported by the hearing it is desirable to keep expansion and distortion of the outer shell to a minimum and this may be aided by providing suitable clearance 58a between the outer edges of the radial partitions 58 and the outer shell 54 at and adjacent to the plane of support which in the present instance is at the plane of the flange ring 92. By means of such clearance the radial partitions are free to expand and contract Without imposing localized radial stresses on the element 92.

The structure just described provides numerous important advantages with respect to both initial cost and upkeep. As to the former, the use of the wire elements 68 to provide the tracks for the balls eliminates the need for providing finely finished surfaces forming the recesses 66 and 76. The wire elements themselves are very inexpensive advantageously being made of piano wire or other high carbon or steel like metal of similar elastic nature. Balls 70 are advantageously of the kind used in standard ball bearings and also may be relatively inexpensive since the action of the bearing is such that a high degree of precision in the parts is not required and balls rejected for use in ordinary ball bearings because of failure to meet dimensional tolerances may readily be used. The reason for this is that the number of balls employed in relation to the weight carried is such that the balls deform the wire rails sufliciently to create narrow tracks on the rails, and the elasticity of the metal of the rails and of the balls themselves is suflicient to compensate for minor dimensional variations. The elastic deformation that is possible with the construction described also insures even distribution of the weight carried by the bearing. Such construction is made practically possible because of the fact that in apparatus of the kind under consideration the speed of rotation of the rotors is only a very few revolutions per minute, so that even in the case of relatively very large diameter rotors the linear speed of operation of the hearing is very low as compared with usual anti-friction hearing applications. Wear is thus very slow, particularly since temperature conditions may be controlled so that the hearing may readily be grease lubricated, one or more channels 102 for introduction of lubricant advantageously being provided in the ring 44. Because of the antifriction nature of the bearing, power consumption is very low.

By virtue of the manner in which the tracks or rails are formed on the rails by the action of the bearing itself, sections or segments of the rails and also individual balls that become unduly worn or otherwise defective can readily be replaced and this easily accomplished because of the removable segmental construction of the parts 50, 78 and 80, giving access from the exterior of the casing to the balls and rails. In the construction shown, balls and rail segments can be removed while the bearing is under load, but ordinarily the insertion of new and undeformed rails will require that the hearing be unloaded and for that purpose the casing shell 48 is advantageously provided with peripherally spaced fulcrum blocks 104 adjacent to openings 106 having removable cover plates 108. Blocks 104 are adapted to be engaged by lifting levers 116 the inner ends of which engage a lifting ring 112 attached to the rotor shell, the levers advantageously being actuated by bolts 114 threaded through suitable fixed supports 116 and adapted to engage the outer ends of the levers.

It will be evident that the bearing construction is such that not only is the bearing member 44 fixed both radially and axially with respect to the end plate 12, but also the upper bearing member 46 which is radially fixed by the balls 70. The rack 84 is thus fixed with respect to the stationary structure carrying the driving gear 86 which enables simple and inexpensive forms of gearing to be used and also makes the apparatus adaptable for friction drive.

The fixed position of the bearing member 46 axially relative to the end plate 12 is highly important from the standpoint of effective sealing, since it maintains the end of the outer rotor shell located in substantially fixed relation axially with respect to the adjacent end plate, regardless of dishing or other distortions of the rotor caused by temperature ditferentials. Since freedom of lateral expansion and contraction of the rotor is permitted by the sliding connection between the rotor flange and the bearing member 46, no stresses arising from rotor distortion are transmitted to the latter. With the end of the rotor thus axially fixed at its periphery, effective sealing between the end plate and the perimeter of the rotor is readily obtainable with a very simple and inexpensive form of seal. In the apparatus shown the peripheral seal 118 is carried by the rotor, advantageously being of known form consisting a multiplicity of leaves of relatively soft and malleable metal clamped to the shell by ring elements 120. Seals of the kind mentioned result in very little wear or power consumption due to drag. since they are substantially free from pressure contact,

6 but obviously can be very effective only between parts having a substantially constant clearance, such as is produced by the present construction.

[n order to aid in maintaining the most constant clearance possible between the rotor shell and the end plate, differential expansion in axial direction between the bearing structure adjacent to the heated rotor and the outer casing ring 50 exposed to the cooler ambient atmosphere should be kept to a minimum. To this end it is desirable to place the hearing at or adjacent to the cold end of the rotor where there is the least radiation from the shell and where the heat that can be transmitted by conduction from the rotor is the least. Heat transmitted to the hearing by conduction is further minimized by the provision of the heat insulating ring 98.

With the outer shell of the rotor axially located at the cold end of the rotor, maximum variation in clearance due to difierential expansion and contraction occurs between the opposite or hot end of the shell and the end plate 14, this variation being too great to permit of a simple and effective seal directly between the shell and the end plate. However, due to the substantially fixed axial location of the rotor shell at one place, comparatively simple and highly efiective sealing means is obtainable for maintaining the desired seal. In the present example, seen most clearly in Figs. 3 and 6, the rotor shell 56 includes at its lower end a cylindrical bearing ring 122 slidably engaged for relative axial movement by a circumferentially interrupted sealing ring 124 held in radial engagement with ring 122 by means of a number of yieldable clamps formed by bolts 126 and springs 128 loading washers 130 bearing on the ring 124. The required relative axial movement is permitted by the slots 132 in ring 124 through which the bolts 126 pass. Ring 124 carries the seal 133 which advantageously is of the same kind as seal 118, this simple form of seal being efiective because of the fact that a substantially fixed or constant axial clearance can be maintained between the ring 124 carrying the seal, and the end plate 14, regardless of movement of the rotor shell due to expansion or contraction. This is accomplished by connecting the ring 124 to the rotor shell at a place where the shell is substantially fixed relative to the casing, by means having minimum relative expansion and contraction relative to the casing. In the present instance the plane where the rotor shell is axially fixed is at the cold end and the sealing ring is accordingly connected to the shell by a plurality of peripherally spaced links 134 anchored by bolts 136 at or near the fixed axial plane of the shell. To minimize relative axial. movement between the ring 124 and the end plate 14 differential expansion between the links 134 and the outer casing must be kept as low as possible. To this end and also to prevent undesirable loss of heat from the rotor, the outer shell is provided with a layer of insulating material 138 to minimize radiation of heat to the links 134 located in the annular space 140 between the rotor and the casing. To prevent heating of the links by conduction, heat insulating means such as washers 142 of heat insulating material, may be used between. the links and their anchoring bolts.

To further aid in minimizing difierential expansion, a small amount of the cooler fluid such as the air to be heated may be bled from the supply duct and caused to flow through the annular space 140 to keep that space and the parts located in it at a temperature more nearly like that of the outer casing than that of the rotor. In the example shown, this is accomplished by providing a bypass connection 144 leading from the cold air duct 20 through the ring 50 to the space 146 outside the hearing 42. A restricted flow of air through the bearing to space 140 is permitted through the narrow throttling slot 148 and this air mingles with the leakage air passing seal 118 and a second peripheral seal 150 on flange '7 92 for restricting the air flow. The air. passing these seals reaches space 140 through holes 152 in the flange. The air admitted to space 140 escapes past seal 133, the pressure drop of the air flowing through the rotor being greater than that flowing through space 140. By means of the heat insulation and the flow of relatively cool air through space 140 the diiierential expansion between links 134 and the outer casing is kept to such low value that effective sealing is secured at the end plate 14.

In addition to peripheral seals, radial seals between the ends of partitions 58 and the end plates is also required, and the present construction also permits of very simple and effective radial sealing regardless of dishing of the rotor, as is shown more clearly in Fig. 6. Referring now to that figure, it will be seen that the end plates are held in fixed spaced relation at the axis of the rotor by means of the spacing bolt 154 and studs 156. Fixed to the end plates, as by studs 158 are annular rings 160 and 162 having external circular grooves 164 and 166 for guiding the radially inner ends of the radial sealing members and holding them in fixed axial relation to the end plates at the center of the rotor. One of the radial sealing members for sealing against the end plate 12 is shown at 168 and is in the form of a plate pivotally mounted at 170 at its outer end by a spring loaded bolt connection which holds the plate yieldably against one of the radial partitions. At its radially inner end the plate 168 is provided with a tongue 172 passing through an axial slot 174 in the end of the inner rotor shell 54 and extending into the guide groove 164. Plate 168 is resiliently held against partition 58 inwardly of the pivot connection 170 by a number of additional spring loaded bolt connections, one of which is indicated at 176, but all such connections operate in conjunction with a slot 178 in the plate which permits relative axial movement between the plate and the partition 58.

The inner rotor shell 54 stops short of the end plate 12 and is encircled by a split sealing ring 188 resiliently held in sliding engagement with the shell by a number of spring loaded bolt connections, one of which is indicated generally at 182 and which permit sliding movement by virtue of slots 184. The ring 180 is held in sealing relation against the end plate by the several radial sealing members the tongues 172 of which pass through appropriate holes in the ring. The plate 168 has clamped to it, as by strip 186 and bolts 188 a sealing strip 190 which may be of any desired known form, advantageously of the same nature as the peripheral seals. It will be seen that with the above described construction the radial seals will be maintained in substantially fixed axial relation to the end plate since for reasons already explained it is evident that the radially outer ends of the partitions to which the outer ends of the plates 168 are pivotally connected, are substantially fixed axially relative to the end plate, while the inner ends of plates 168 are axially fixed relative to the end plates by the ring 160. Likewise, it will be evident that the rotor can warp or dish with reference to the flange 92, which represents the axially fixed element of the rotor, without disturbing the radial seals, since the inner portions of the partitions and also the inner shell 54 can move freely in axial direction relative to the radial sealing members.

The lower sealing members, comprising plates 192 and strips 194, are associated with the lower guide ring 162 and inner peripheral seal 196 in the same fashion as the above described upper sealing members, but the lower plates 192, instead of being pivoted at their outer ends to the partitions extend through slots 198 in the lower end of the outer shell and terminate in tongues 200 passing through appropriate holes in the lower peripheral sealing ring 124 which, for reasons previously discussed, is substantially fixed axially relative to end plate 14.

As seen in Fig. 6, the inner rotor shell may be reinforced by transverse plates 202, but in such case openings 204 are provided which give greater radial clearance around the spacing bolt 154 than there is between the peripheral rotor flange 92 and the shoulder on the upper bearing member 46, the latter being depended upon for radial centering of the rotor.

As previously noted it is ordinarily preferable to have the outer rotor shell fixed axially at the cold end of the exchanger and for installations where the flow of the fluids is such that the cold end of the apparatus the supporting bearing can readily be mounted at the lower end, as illustrated by the construction shown in Fig. 7. Comparison of Figs. 7 and 3 makes it immediately apparent that the two structures are the same in major respects and function in the same way to secure the desired results, the

principal difference being merely a rearrangement of parts relative to the rotor. The bearing construction is the same and functionally corresponding parts are designated by like reference characters.

In the present embodiment the lower bearing member is mounted at the lower end plate 14 and the outer ring of channel members supports an annular ring member 206 which carries the standards 36 upon which the upper end plate 12 is mounted. The supporting flange member 92 is located adjacent to the bottom end of the rotor and the sealing strip 150, which limits inflow of air from bypass 144, bears against the ring 206 rather than an end plate. Also, the sealing strip 118 which is axially fixed on the rotor shell, is at the bottom of the latter and bears on end plate 14, while the sealing ring 124 which is axially movable on the rotor shell, is located at the top so that the sealing strip 133 bears against end plate 12. While the radial seals do not appear in Fig. 7 it will be understood that their construction may be the same as shown in Fig. 6, except that in the present arrangement the bars 168 that are pivotally mounted at their outer ends are located at the bottom of the rotor for carrying the seals for end plate 14.

While as previously noted, it is desirable to have the axially fixed plane of the outer shell of the rotor at or close to one end and preferably the cold end, other considerations may make it desirable to have the fixed plane located intermediate the rotor ends and in Fig. 8 there is illustrated such an arrangement with the fixed plane of the shell located approximately midway of the length of the rotor. In this example the bearing construction and arrangement is like that previously described, the bearing assembly being located, however, between the parts 36a and 36b of the divided standard 36. The general arrangement is essentially as shown in Fig. 7, and corresponding parts bear like reference characters. The primary difference in the constructions is due to the fact that the fixed plane of the rotor shell is materially spaced from both end plates of the casing structure, no seal axially fixed on the rotor shell, such as seal 118 of Figs. 3 and 7, being employed. Instead, seals 133a and 133k corresponding to seals 133 of Figs. 3 and 7 and mounted on axially slidablc sealing rings 124a and 12% are employed for sealing against both end plates. In the construction shown rings 124a and 124b are connected by links 134 anchored by studs 136 to the axially fixed flange 92. Obviously separate sets of links can be employed to connect each sealing ring to the rotor.

As in Fig. 7 the radial seals do not appear but again they may be of the construction described in connection with Fig. 6, except that in the present instance the radial plates at both ends of the rotor are constructed and arranged like the plates 168 of Fig. 6, being connected at their outer ends to the rings 124a and 1241) respectively.

Also the lifting arrangement for the rotors shown in Figs. 7 and 8 has been omitted from the broken drawings for purposes of simplification but it will be understood that such arrangement is intended to be included in the constructions shown in these figures.

In all of the previously described embodiments the 9 inain bearing 42 has been of the kind in which both hearing members, whether built of a number of segments or otherwise constructed, are peripherally continuous. In the case of bearings to be used with rotors of very large diameter, and in very high temperature applications, it may however occur that there may unavoidably be a sufficient differential expansion between the upper and lower bearing members due to temperature difference to make it advisable to make either or both of the bearing members of relatively movable segments permitting radial enlargement and contraction of the members while still retaining the coaxial alignment of the bearing tracks.

In Figs. 9 and 10 one such arrangement is shown, embodied in an organization arranged like that of Figs. 1 to 3. In the present arrangement the upper bearing member 46, instead of being a peripherally continuous ring is formed by a plurality of ring segments 72a, 72b, 72c, etc., independently movable in radial direction relative to the rotor flange 92, and individually guided thereon by radial keys 208 secured by studs 210 to the segments and sliding in suitable keyways 212 in the flange 92. To each of the segments of ring 72 there is fixed by means of studs 82 a separate segment of the outer ring 80 carrying the rack 84. From Fig. 10 it will be noted that each segment of the ring 80 is peripherally slightly offset with respect to the segment of ring 72 to which it is fixed so as to provide overlapping joints between the peripherally contiguous assemblies of segments.

As previously noted either bearing member may be made with independently movable segments and in Figs. 11 and 12 an example is shown in which the lower bearing member is of expansible segmental construction. In this case the lower bearing ring 44 is provided with a plurality of peripherally spaced radial keys 214, each of which locates peripherally and guides a ring segment such as 44a, 44b etc. (Fig. 12). With this arrangement, in order to prevent too great a flow of cooling air between the ring segments 44a, 44b, etc., a seal 216 is advantageously provided between the upper and lower bearing members. While in most instances the arrangement shown is advantageously used with a peripherally continuous upper bearing member, and with the rotor centered by that member, it is possible if desired to combine the expansible lower bearing member constructions of the embodiment shown in Fig. 11 with expansible upper bearing member construction of the kind shown in Fig. 9.

For numerous reasons it is highly desirable to have the upper bearing member, particularly when it constitutes the driving element for the rotor, subjected to the minimum in the way of stresses due to heat or other factors and tending to distort it. Consequently in most cases it will be found desirable to provide for relative lateral movement between the bearing member and the rotor shell which it carries. In the embodiments of apparatus previously described, this lateral movement has been provided for between a lateral bearing surface on the bearing member and a complementary bearing surface on the rotor flange, these surfaces being freely movable relative to each other laterally within fixed limits, the weight of the rotor providing suflicient loading to cause the rotor to be turned by the frictional contact between the laterally extending bearing surfaces.

Other means however, may be employed for effecting a connection between the upper bearing member and the rotor which will permit the desired relative movement laterally between the connected parts and in Fig. 13 one such construction is shown in an organization of the general character illustrated in Fig. 3. In the present embodiment, the ring parts 72 and 80 of Fig. 3 are combined to form a ring 216 which may or may not be segmental, and which is connected to the upper flange 92 of the rotor by a plurality of peripherally spaced links 218 secured by studs 222 and 220, the web portions 218a of the links being of sufliciently thin section in radial direction to flex 10 enough to compensate for rotor distortion without iniposing undesirably high stresses on the ring 216.

Instead of the link arrangement shown in Fig. 13 the connection may be in the form of a flexible diaphragm structure of the kind shown in Fig. 14, in which the ring member 72 is connected to the rotor flange 92 by a flexible diaphragm member having a number of peripherally spaced Webs 224 functioning like the links 218 of Fig. 13.

When arrangements such as those shown in Figs. 13 and 14 are employed, centering of the rotor within a selected clearance space inside the main bearing may not be feasible, and in such cases the desired centering is obtainable by means such as that shown in Fig. 15 in which a bearing sleeve 226 carried by the plate 202 cu gages the distance bolt 154 at the axis of the rotor.

Also when links or flexible diaphragm members are employed to connect the rotor shell with a bearing member, the total cross section of the connecting metal may be sufiiciently small so that the quantity of heat conducted through them may be little enough to render the use of any heat insulating material quite superfluous.

From the foregoing it will be obvious that the principles of the invention may be carried into effect by means of a wide variety of specific structural embodiments, that various features may be combined in different ways and that certain features may be employed to the exclusion of others. The invention is accordingly to be understood as embracing all forms of apparatus falling within the scope of the appended claims.

What we claim is:

1. A regenerative heat exchanger of the vertical type comprising a rotor; a stationary casing enclosing said rotor; a bearing construction including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearing member having a raceway on the under side thereof, and anti-friction bearing elements in said raceways for maintaining the members in axially spaced relation; the rotor having supporting means disposed at its periphery mounted to the rotatable bearing member; one of said bearing members being coaxial with the rotor and the other being radially displaceable relative to the casing to register the raceways with each other.

2. A regenerative air preheater as claimed in claim 1, in which the rotor is centered at its center.

3. A regenerative heat exchanger of the vertical type comprising a rotor having a shell provided with outward projections extending perpendicularly thereto; a station ary casing enclosing said rotor; a bearing construction including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearing member having a raceway on the under side thereof, and anti-friction bearing elements in said raceways for maintaining the members in axially spaced relation; said projections being supported in a radially slidable manner by the rotatable bearing member; one of said bearing members being coaxial with the rotor and the other being radially displaceable relative to the casing to register the raceways with each other.

4. A regenerative heat exchanger as claimed in claim 3, in which a heat insulating layer is provided on the surface of the rotatable bearing in contact with said outward projections on the rotor.

5. A regenerative heat exchanger as claimed in claim 3, in which the rotatable bearing member provides a rotor centering shoulder coacting with said outward projections on the rotor.

6. A regenerative heat exchanger as claimed in claim 3, in which said projections on said rotor form an annular flange.

7. A regenerative heat exchanger of the vertical type comprising a rotor; a stationary casing enclosing said rotor; a bearing construction including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearing member having a raceway on the under side thereof, and anti-friction bearing elements in said raceways for maintaining the members in axially spaced relation; flexible link means attached to the rotor at the periphery thereof and to the rotatable bearing member; said link means being provided for radial movement between said rotor and said rotatable bearing member to register the raceways coaxially with each other.

8. A regenerative heat exchanger of the vertical type comprising a rotor; a stationary casing enclosing said rotor; a bearing construction including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearing member having a raceway on the under side thereof, and anti-friction bearing elements in said raceways for maintaining the members in axially spaced relation; flexible diaphragm means attached to the rotor at the periphery thereof and to the rotatable bearing member; said diaphragm means being provided for radial movement between said rotor and said rotatable bearing member to register the raceways coaxially with each other.

9. A regenerative heat exchanger of the vertical type comprising a rotor; a stationary casing enclosing said rotor; a bearing construction including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearingmember having a raceway on the under side thereof, and anti-friction bearing elements in said raceways for maintaining the members in axially spaced relation; the rotor having supporting means disposed at its periphery mounted to the rotatable bearing member; one of said bearing members being coaxial with the rotor and the other comprising a plurality of peripherally spaced and radially displaceable segmental sections to register the raceways with. each other.

10. A regenerative heat exchanger as claimed in claim 9, in which the rotatable bearing member is divided into said segmental sections.

' 11. A regenerative heat exchanger as claimed in claim 9, in which the lower supporting bearing member comprises a plurality of radially movable segmental sections in keying engagement with the stationary casing.

12. A regenerative heat exchanger of the vertical type comprising a rotor; a stationary casing enclosing said rotor; a bearing construction including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearing member having a raceway on the under side thereof, arcuate wire elements embodied in the corners of said raceways and anti-friction bearing elements in said raceways for maintaining the members in axially spaced relation; the rotor having supporting means disposed at its periphery mounted to the rotatable bearing member; one of said bearing members being coaxial with the rotor and the other being radially displaceable relative to the casing to register the raceways with each other.

13. A regenerative heat exchanger of the vertical type comprising a rotor; a stationary casing enclosing said rotor; a bearing construction including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearing member having a raceway on the under side thereof, and anti-friction bearing elements in said raceways for maintaining the members in axially spaced relation; the rotor having supporting means disposed at its periphery mounted to the rotatable bearing member; one of said bearing members being coaxial with the rotor and the other being radially displaceable relative to the casing to register the raceways with each other; and driving means provided on the rotatable bearing member for peripheral drive of the rotor.

14. A regenerative heat exchanger as claimed in claim 13, in which said driving means comprises a plurality of segmental sections forming together a pin rack drive.

15. A regenerative heat exchanger of the vertical type having countercurrent flow of a hot and a cold medium and comprising a rotor; a stationary casing enclosing said rotor; a bearing construction located at the end of the casing where the cold medium enters and cooled medium is discharged and including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearing member having a raceway on the under side thereof, and anti-friction bearing elements in said raceways for maintaining the members in axially spaced relation; the rotor having supporting means disposed at its periphery mounted to the rotatable bearing member; one of said bearing members being coaxial with the rotor and the other being radially displaceable relative to the casing to register the raceways with each other.

16. A regenerative heat exchanger of the vertical type having countercurrent flow of a hot and a cold medium and comprising a rotor; a stationary casing enclosing said rotor; a bearing construction including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearing member having a raceway on the under side thereof, and anti-friction bearing elements in said raceways for maintaining the members in axially spaced relation; the rotor having supporting means disposed at its periphery mounted to the rotatable bearing members; one of said bearing members being coaxial with the rotor and the other being radially displaceable relative to the casing to register the raceways with each other and peripheral sealing means disposed at the ends of the rotor to seal against said end plates of the casing, sealing means at the end of the rotor adjacent the end where the cold medium enters being rigidly attached to said rotor end, and the sealing means at the other end of the rotor being carried by a circumferentially interrupted ring connected to one end of peripherally spaced links which at their other end are anchored at the end of the rotor where the cold medium enters, said ring beingaxially movable relative to the rotor and held in radially yieldable engagement with the rotor.

17. A heat exchanger as claimed in claim 16, which includes radial seals at each end of the rotor, said radial seals at the end of the rotor where the cold medium enters being pivotally mounted relative to the rotor at their outer ends, and the radial seals at the other rotor end being secured at their outer end to the links carrying the peripheral seals disposed at said end, the respective radial seals being guided at their inner ends in the center of the rotor.

18. A regenerative heat exchanger of the vertical type having countercurrent flow of a hot and a cold medium and comprising a rotor; a stationary casing enclosing said rotor; a bearing construction located at least more adjacent the end of the casing where the cold medium enters and cooled medium is discharged than the opposite end of the casing and including a lower supporting bear-' with each other; and means provided to supply cooling medium in the space between the rotor and the casing via said bearing construction.

19. A regenerative heat exchanger of the vertical type having countercurrent flow of a hot and a cold medium and comprising a rotor having a shell and radial partition walls dividing the rotor into sector shaped compartments but providing each a clearance space between respective partition walls at the end of the rotor Where the cold medium enters and cooled medium is discharged; a stationary casing enclosing said rotor; a bearing construction including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearing member having a raceway n the under side thereof, and anti-friction bearing elements in said raceways for maintaining the members in axially spaced relation; the rotor having supporting means disposed at its periphery mounted to the rotatable bearing member; one of said bearing members being coaxial with the rotor and the other being radially displaceable relative to the casing to register the raceways with each other.

20. A regenerative heat exchanger of the vertical type having countercurrent how of a hot and a cold medium and. comprising a rotor; a stationary casing enclosing said rotor; a bearing construction located about halfway between the ends of the casing and including a lower supporting bearing member mounted substantially fixed against rotation on the casing and having a raceway on the upper side thereof, an upper rotatable bearing memher having a raceway on the under side thereof, and antifriction bearing elements in said raceways for maintaining the members in axially spaced relation; the rotor having supporting means disposed at its periphery mounted to the rotatable bearing member; one of said bearing members being coaxial with the rotor and the other being radially displaceable relative to the casing to register the raceways with each other.

References Cited in the file of this patent UNITED STATES PATENTS 1,823,481 Zander Sept. 15, 1931 2,010,752 Dubus Aug. 6, 1935 2,055,071 Eriksson Sept. 22, 1936 2,306,189 Schweickart et al Dec. 22, 1942 2,313,084 Manly Mar. 9, 1943 2,364,951 Corte Dec. 12, 1944 2,465,497 Turrettini Mar. 29, 1949 2,468,419 Weber Apr. 26, 1949 2,540,733 Holm Feb. 6, 1951 2,545,122 Thompson Mar. 13, 1951 2,598,182 Kolb May 27, 1952 2,605,646 Karlsson et a1. Aug. 5, 1952 2,607,565 Jensen Aug. 19, 1952 2,672,378 McVey Mar. 16, 1954 2,674,898 Mudersbach Apr. 13, 1954 2,692,760 Flurschutz Oct. 26, 1954 2,696,743 Odman Dec. 14, 1954 2,744,731 Brandt May 8, 1956 2,803,508 Nilsson et a1. Aug. 20, 1957 

